Telephone-exchange system



Fb. 25, '1930. H. M. BAscoM ET AL 1,748,166,

TELEPHONE EXCHANGE SYSTEM Filed Sept. 23, 1927 ,1 v JW Patented Feb. 25, 1939 UNITED STATES YHlaivlt'rla. BAsCoM, oF BROOKLYN, NEWYORK, AND WILLIAM T. HAINEs, 0F yMOUN- PATENT OFFICE TAIN LAKES, NEW JERSEY, ASSIGNORS TO AMERICAN TELEPHONE AND TELEGRAPH Y y COMPANY, A CORPORATION OF NEW YORK TELEPHONE-EXCHANGE SYSTEM Application med september 23, 1927. serial No. 221,559.

This invention relates to telephone exy change systems rand particularly to improvements in party line message registration.

Its object is to enable the performance of a more positive and reliable test of party lines to determine the station originating the call.

According to this invention the substations of a party line are equipped each with a test relay to enable a plurality of separate tests to be made from thecentral office to determine the calling station. Y

A feature ot' the invention is a system in which the source of talking current is applied to the line on either originating or terminating callsin such a direction as to operate or not operate the substation relay to insure the removal of ground connections from the talkf system.

ing circuit.

Thedrawing shows theinvention applied to a four-party line in an automatic telephone The substations A, B, C and D of the party line 10 are equipped with polarized relays 1 to 4 respectively'. Relays 1 and 4 are polarized in such a manner that they operate when the negative pole of the current source is connected to the ring conductor of the line and the positive pole is connected to theA tip side'. The relays 2 and?) are polarized to respond to current flowing in the opposite direction. It will be noted that relay 1 when deenergized extends a ground connection through the switchhook contact directly to the tip side of the line 10. The relay 2 when deenergize'd extends a ground connectionv through the switchho'olr contact, the talking transmitter and contacts of the dial 6 to the ringr side ofthe line 10. yRelay 3 when operated extends a ground connection to the ring fside of the line and relay 4 when operated connects ground to the tip side of the line.

At the'central oftce the line terminates in a line finder switch F illustrated diagrammatioally by the'brushes 13 to 19 inclusive. The line finder F is connected to the lett windings of a repeating coil 29, the right hand windings of which may be connected directly to the brushes of a selector switch. The line iind er andselector unit may be of substantially Vthesame construction and operation as illustrated and described in detail in the patent to Kopp No.l 1,589,402, granted June 22, 1926.

The control and operating circuits for a selector switch of this character are also shown anddescribed in the patent to Stearn et al., No. 1,395,977, granted November 1, 1921.

The sequence switch 6() controls the line finder and district circuits and is partly illustrated in the drawing. vThis switch may be of the well-known type describedin the patent to Reynolds et al., 1,127,808, grantedFebruary 9, 1915.

A step-by-step single movement control switch having the brushes 20 to 25 inclusive and'stepping magnet 40 is also provided for controlling the circuits. The line 10 is further provided with message registers 47 to 50 inclusive, one for each of the four stations on the line.

On calls extended to the party line 10, one of ouriinal selector terminals may be used depending upon the party called. These four terminals S. S1, S2 and S? are illustrated diagrammatically. Y

By means of the testing devices located at the central oflice and the polarized relaysat Vthe individual stations, a number of separate tests may be made to definitely determine which station on the party line has originated a call. First a test is made to determine whether the calling station is one of the two stations A and B or one of thestations C and D. Next a test is made by applying current to the line in such a direction as to operate one relay and not to operate the other relay of the pair already determined. After the relay operates it removes ground potential from one or the other sides of the line in one case. In another case it the relay operates it applies ground potential to the tip or to the ring sideoi' the line.` The third test is made by applying current to the line in the opposite direction ,such that if the relay at t-he g calling station is operated on the second test the relay remained inert to withhold ground potential from the line or to maintain ground potential on the line it operates on the third test to establish the opposite condition. By

e magnet 40.

means of these-three tests a check is secured to insure that the Ycondition found on one or another of the tests is a true identifying condition and not one which has been brought about either accidentally or due to an attempt on the part of the subscriber to defeat the charge.

A detaileddescription will now be given, assuming that the partyat the substation A initiates the call. rThe initiation of the call causes the operation of the line finder F to seize the subscribers line 10.' TheI calling line.

is thus extended over the brushes 13 and 14 and the wipers 20 and 21 in the lirst position through contacts and 31 ot sequence switch 60 to the register sender 32. in the well-knownmanner, the sequence switch 60 in response tothe initiation of' the call advances the 'contacts 30 and 31 to the closing position. Also battery potential is applied to the brush 15 to operate the cut-o relay 12 which opens theusual circuit for the line relay 11. The calling subscriber manipulates his dial' 5 and sets up a record of the wantedL Ydesignation at the register sender The register sender proceeds to control the selective switchesto establish the connection.

During thev processes of establishing the connection the sequence switch 60 arrives in some position such as position 12. As soon after the 4sequence switch reaches position 12 as the interrupter 46 closes, a circuit is established over the contact 41 for thestepping Magnet energizes and, on the next opening of the interrupter, deenergizes to advance the brushes 20 to 25 inclusive to their second position. l `v Y In position 2 .of they control switch, a-test circuit is closed from the positive pole ofbattery, through the winding oi test relay 35, wiper 20, thence through the brush 13 over the tip side of the line 10 through the switchhook contacts at station A, bacll: contact of relay 1A to ground.k The ring side of the line is openy at this time and hence no circuit is completedfor the polarized relay 1. v The relay 35 operates in the circuit traced and closes an obviouscircuit for relay 37. `Relay 37 locks through its winding and Contact to ground. The locking circuit of relay 37, and also ofl locking circuits of relays 38 and 39, extend througha sequence switch contact or Y a relay contact (not shown) whiclrinay be opened at some convenient time toV permit the release of these relays.

l The switch Vcontinues to step under the control'of interrupter 46 and advances into position 3. The test circuit through thezwinding ro f relay is maintained ink both positions 2 `and 3 giving the relay suliicient time in which tooperate; v

- v"VVhen fthe control switchy reaches position- `4,the relay 35 releases and a second test circuit isffclosed from the negative pole of battery, through the right l windingn of test rethrough the Ytalking transmitter 52, normal Ycontacts of the dial 5, Winding of polarized relay 1, returning on the ringV side of the line through the wiper 21, lett winding of test relay 36 to ground. The flow or" Ycurrent in this circuit is in the opposite direction from that required to operate relay 1. Accordingly relayl remains inert. Relay 36 is ditterentially wound so that when current flows through hothits windings the relay is balanced anddoes not attract its armatures. Since the relay 1 does'not operate in this caseV it maintains a, grounded connection through' its back Contact and through the switchhook contactV to the tip side ofthe line 16. This results in a short-circuit ofthe lett windingvk of relay 36; Accordingly, relay 36, which is slow to operate, attracts its an interval.

test circuit through relay 36 is'maintained armature after and, the relay being operated, a' circuit 'is completed from ground through its Contact, wiper 25, in its fifth position, winding of relay 38 to battery. Relay38 operates and locks. f n

On the next step of the controlswitch it moves into position .'6, opening the previously traced circuits through the windings ofV relay 36. A third test is made at this time and the circuit Vtherefore may be traced from ground through .the left winding oit relay 36, wiper 20, ythence over the tip side oic the line throughy vswitchhook contacts 'at station A,

transmitter 52, contacts of theA dial glwinding of relay 1 and returning/over the ring side of the line through the right winding of i i relay 36 tothe negative pole.otbattery.V VThe flow of current in'this circuit is in the proper?Ar rdirection to operate the polarized relayv 1.

Relay 1Y immediately' removes the ground f connection from the tip side ot the line, preventing the lett winding of relay'36 from being short-circuited. kWith current flowing throughrboth windings of relayv 36 it releases and maintainsrits armaturein' its normal position. Y x y y i Y On the neXt step or" the control switch the relay 36 remains inert toy indicate that the` ground potential has been Aremoved from the tip side of the line alt-the callingr station A. 1 Finally, the control switch'advances into its last position where .itremains` In this position the tip andring conductors ofthe line areezztended over-wipers 20. and'21 through sequence switch contacts. 26 and 2T and the lett windingsof repeating coil 29 to vbattery through the back contacts of reversingrelay28. v v

In the well-knownfmanner, the sequence switch advancesA into the tal-hing position and conversationv talres place. .Following conversation, .the subscribers `f-replace..their recensire Q11- th@ sirichhoekeead the Sea-eene@ llU Ation into position 18.

switchy 60 is advanced 'from the talking posi- While the sequence switch is moving through positions 15 to 17 inclusive a`circuit is completed frombattery through the resistance 45, contact of relay 44, contact 43, right back conta'ctvoi relay 39, kinner left front contacts of relays 38 and 37,

and brush 16 through the winding of message register 47 to ground. rlhe register `47 is operated to charge thecall to the party at substation A.' When the sequence switch reaches position 18 a circuit is closed from battery through the winding and contact of.-magnet 40 to ground at the contact 41. Magnet 40 interrupts its rown circuit and steps released in any suitable manner.4

It the ycall 1s originated at substation B, the'firstv test takes place 1n the same manner resulting inthe operation of relays 35 and 37.

In this case,'the test circuit is traceable from the positive pole of battery through the windy ingxot relay 35, thence over the tip side of the line, through the winding of relay 2, and

the switch hook contacts, and the 4back con-v f'tact 'of relay 2 to ground. The relay 35 operates,`butv the direction of current fiow is suchthat the relay 2 does not operate.

f The second test is made by completing a circuit from battery through the right winding of the diierential relay 36, thence over the tip side of the line through the winding ofrelay'2, switchhook contacts and theback Contact of relay 2 to ground. Current flows in the proper direction in this circuit to operate the relay 2. Relay 2 operates before relay.. 36V has an opportunity to attract its armature. Relay 2 in operating disconnects '1 the ground potential from the ring conductor of the line so that the test circuit now leads through the L winding of relay 2, thence through the switchhook contacts, talking transmitter 62, contacts ofdial 6 and returning over the ring side of the line through the 'leftwinding of relay 36 to ground. lVith current flowing through both windings of relay 36 it does not ,attract its armature.

, The third test of the substation B is performed by applying current over thetest ciry vcuit in the opposite direction so that relay 2 will release to reestablish vthe connection from ground to the line. y This circuit leads from battery through the right windingot1 relayf36, thence over the ring side or" the line through contacts of thedial 6, transmitter 62,

switchhook contacts, windings ofrelay 2, and

` returning'over the tip side of the kline through the left winding off relay n .positive pole of battery. Relay'2 releases'in 36 to the grounded this circuit and short-circuitsr thev lett Windingofr relay "36. This causes relay 36 to operateiandfwhen the control switch steps into n L *positionV 7 circuit is closedvfrom ground through the contact of relayy 36,-wiper'25, to

through the right front contact ot' relay 39,.

outer left contact of relay 38, outer leiit front contact of relay 37, brush 17, back Contact of the line relay 11, winding of the message register 48 tor ground. The register 48 operates to charge the, call against they party at substation B. The purpose of relay 28 will be explained hereinafter.

It thecall originates at substation C the iirst test iinds no .ground potential on either side of the line since the relay 3 is normally deenergized. Accordingly, relay 35 remains inert. Y

Gn the second test current is applied to the line'in such a direction as to operate the relay 3. Relay 3 in operating short-circuits the lett winding of relay 36 causing the latter relay to energize. Relay 36 in operating completes a circuit from ground through its contact, wiper 25 in position 5, winding of relay Thus the call is charged to the vparty at substation C.

If the call originates at'substation D the first test is made by attempting to complete a circuit for relay 35. This circuit is vheld open, however, at the relay 4 and consequently relay 35 does not operate.

On the second test, negative potential is appliedv to the tip conductor of the line and positive potential to the ring'conductor. In this case the relay 4 does not operate and accordingly the relay'36 remains neutralized and inert,

Lastly, when the third test is made, current is applied in the opposite direction resulting in the actuation of relay 4 which short-circuits the left winding ot' rela-y 36. Relay 36 in the manner explained applies a ypotential to conductor 63 resulting in the op- 'eration of relays 28 and 39.

The metering circuit in this case may be traced through the contact 43, right front contact ofrelay 39, outer left back 'contacts of relays 38a`nd 37 brush 19, through the winding of message register l to ground, charg ing the call to the substation D.

It will be noted that the relay 28 operates whenever a call is initiated by thesubscriber in the direction necessary vto insure the removal of ground connections at the substation. l/V hen the substation A initiates a call,

Y the relay 1, having its back contact connected to ground, should be operated during the conversation to remove the ground connection. By observing the direction of current ow required to operate relay A it will be seen that this is 'secured by applying the talkin'g'current through the back contacts of therelay 28. AWhen the party at substation B originates the call the talking current should be applied in the opposite direction in order to operate the relay 2. This is accomplished as above explained by operating the relay 28. K When the'call originates at station C current should be applied in such a direction as not to operate the relay 3. The same is true .of .substation D.

On calls extended to the line asa called line, the'talking current supplied from the Y switches through the brushes of the final sey lectors to the terminals S, S1, i 2 andSS, also flows in such a direction as to insure the removal of ground connections from the line at the substations. If it is assumed that the negative pole of battery is connected to the ring side of the circuit in the-selector switch it will be found on tracing the connections that the directionof current flow'will be such in every case that the ground potential at the substation is removed. This is accomplished by reversing theconnections lea-ding from two of the selector switches at theframe 65.

y Vhile the invention has been applied to a system employing switches of a given type it is to be understood that the construction and operation of theswitches are unimportant and that the invention is applicable to a variety of types of ,telephone systems.

What is claimed is:

l. In a telephone system, a line having a plurality of .substations, means for establishing an identifying conditionat each station,

means for testing for the condition identify- ,n ing a vparticular station, means for altering Athe condition at said station, and means for making a test to verify that such' alteration has been made. y A

2. In a telephone system, a line having a plurality of substations, means for establishing an identifying condition at each station, vmeans for making a test for the identifying Condition at a particular station, means for Vchanging the condition at said station, means `for making another testto verify that the #condition has been changed, registers, one

for each station, and means controlled by said test vmeans for selecting and operating said registers. ,e 7

3; In combination, a line having a number ofj-stations, meansat each station for placing an identifying condition on said line, means for making a test for the identifying condition pertaining to Vany particular station, means at such station for removing said condition from the line, and means-for testing the line to determine if it is Yfree of Vsaid Ycondition.` Y f 4. In combination, a line having a plurality of stations, relays, one at each station, means at each station for placing an identifying condition on the line, means for mak- .ing a test for the condition pertaining to a particular'station, meansy for operatingthe-I relayat such station to remove the condition yfrom said line, means for testing the line to determine ifi it isfree from said condition, registers, one foreach static-maand means controlled by said testing means to select and operate the register for said particular station.

5. In a telephone system, a line having a plurality of stations, a central otlice, means for establishing an identifying condition at each station, means at the central office to test for the condition at a calling station','means `at the central ctlice to change the identifying condition at such station, and means for making a further test to determine if Athecondition has been changed. 'f Y Y 6. In combination, a telephone linehaving a plurality of stations, relays, one atreach station, certain of said relays serving lwhile inert to apply identifying conditions to` said i line, other of said relays serving while operated to Vapply identifying lconditions there'VV to, and means for making separate testsfof any station, one of which operates andanother of which does not operate-the correspending relay. Y c. n 7. In a telephone system, a line having a number of stations, means at each station for f applying an identifying condition to said line, a source of talking 'current for supplyingthe line, and means for connecting said source to the line in such amanner as to insure theremoval of the identifying condition from the line atthe calling substation.

8. In a telephone system, a line having a number yof stations', `means .at each station for applying anidentifying condition to said line, a source Vof talking 'current forsupplying the line, and ymeans dependenton Vwhich station is calling for varying ne connection Y 'of said source to the line to insure the removal of said condition during conversation;

l9.*InY combination, a'party-line, means at each substation on the line'forv applying an identifying condition to said line,.means for testingthe line for an identifying condition, registers controlled by said testing means,a

source of talking current, andv means for Y variablyconnecting said source to thelinepto cause the removal of the identifying condition vduring conversation.

y. 10. In combination, a party line, polarized relays, one at each substation, means con# trolledy by one relay in its operated condition and by another relay in its unoperated condi` tion for applying an identifying potential to said line, a source of talking current, and means for connecting said source to the line in such a direction as to operate 0r not to op erate said relays.

In testimony whereof, Weshave signed our names to this specification this 16th day of September, 1927. v

y, HENRY M. BASCOM.

WILLIAM T. HAINES. 

